Corbrastang

Did the 427/390hp Vettes come with forged or cast pistons? What was the cc volume? Were they domed?

Thanks

63Corvette

CAST! ONLY HiPo engines had forged pistons, and all of them (solid lifter) had forged pistons regardless of displacement. If you run solid lifters in a 390 or 400HP and consistently run it over 6000rpm, the pistons willl fail catastrophically.....ask how I know.

Corbrastang

Thanks! I just pulled a cylinder head on my 66 427 engine that the previous owner had rebuilt and this is what i found.

Cast 30 over pistons that look like clevite part number 224-2940
Does anybody know or can anybody help me find the cc head volume of these pistons?
Do they look like the stock pistons that were used in the 427/390 vettes?
Will they be ok with todays gas?

landshark 454

They will work if you are not going to be constantly wailing on it. The stock 390 hp redlined at 5500. A slight cam will go to 6000. If you plan on beating this thing hard over 6000, that is another story.

Those are nothing like the original pistons, and are lower compression, generic units. Note the intake valve relief on both top and bottom. These are designed to work on either bank. From all of your pictures from the various posts, I am not impressed with whoever built this engine. You have paint all over the bottom end, poor head surfaces, and generic pistons, Rods out of sequence, though that could be for balance. You may want to have this torn down and inspected by someone who knows engines, and have the clearances and machine work checked.

Are those lower water ports plugged? It has been a while since I have had a big block down and the memory is getting poor. The left one is probably just corroded from the head openning, but the center one makes me wonder.

Corbrastang

I think i am going to go ahead and take the whole thing apart and drop it off at my machine shop on Monday. There is just too much that makes me nervous about the previous work. Whats another couple of bucks at this point to make sure it runs correctly. The last thing i want to have to do is pull the engine after the whole car is assembled.
Im looking at some nice domed forged pistons on summit that will put the car back to its original compression ratio.
Funny, the previous builder used ARP bolts on all external parts, ARP screw in studs on the heads, comp cams pushrod retainers, new stock valves, new springs, new lifters, new cam, new timing chain, and arp rod bolts, but did not bother to surface the heads. I dont see where any metal was removed or added to the crankshaft and that makes me nervous.

Avispa

Those pistons don't have a stock dome configuration at all. The stock dome is 18 cc, and is offset toward the spark plug side of the cylinder to match the location of the combustion chamber in the head.

As 63Corvette said, the stock 390/400HP pistons are all cast. If you want to keep the stock 10.25:1 compression but have forged pistons, Speed Pro has a forged replacement, part number L-2300.

BTW, the factory L-72 solid lifter cam is a great match with the 390/400 HP oval port heads.

The chamber volume in the head is about 108 cc.

midyearvette

...couldn't have said it better.....hard to believe someone did the heads without cleaning the surfaces....take it all down and do it right....landshark is spot on about the pistons and the block.......

Corbrastang

im just back and forth and back and forth on what to do with this block. It will cost me about 1500.00 to get everything checked out and new forged pistons installed, but I know that it is probably the right thing to do. I have 59 invested in the car and i am watching these prices at the mecum auction and it makes me want to hurl.

I thought the cc rating on the heads was 98cc.

Can somone confirm what the volume is on part number 3872702 cylinder heads.

Thanks!

Also, what is the standard deck heigth on a 427?

midyearvette

should be 98.4 cc......9.8 deck

67L36Driver

Those look a lot like the ones I used in mine and I run 87 octane. (3933148 heads 109 cc) Unfortunatly I cannot find the original part number we used.

Corbrastang

I cant find any information on these pistons. They appear to be around a 5cc dome when the valve reliefs are taken into account,but i could be wrong. I called clevite and they have apparently put there piston expert on it. I would think they would have that information readily available